Dynamics of supraglottal flow structures and sound generation in phonation

Abstract

Within the fully-coupled multiphysics process of phonation the fluid flow plays an important role in the sound production. Therefore, the study addresses phenomena in the flow downstream of synthetic self-oscillating vocal folds and their influence on the sound production. A test setup consisting of devices for producing and conditioning the flow including a test section was used. The supraglottal channel was developed to prevent acoustic coupling to the vocal folds. Hence, the oscillations were aerodynamically driven. The vocal folds consist of silicone rubber having homogenous material distribution. The flow was visualized in the immediate supraglottal region using a laser-sheet technique and a highspeed camera. The flow shows asymmetric behaviour in cases with channel. The glottal jet is bend to one side depending on the turbulent flow conditions in the channel. In cases without channel, the jet was stabilized by the constant ambient pressure being symmetrical at each instance during an oscillation cycle. Additionally, the acoustic response of the studied supraglottal cases was investigated in an anechoic chamber. The spectral analysis of the data turns out differences in tonal and broadband parts of the acoustic spectrum. The context to the visualized flow structures will be discussed. © 2013 Acoustical Society of America.